Responsiveness Issues

/****************************************
GENERAL
*****************************************/
body {
  font-family: 'Varela', sans-serif;
  font-size: 1.25em
}


#wrapper {
  max-width: 80%;
  margin: 20px auto;
  padding: 25px 5%;
}

a {
  text-decoration:none
}

img {
  max-width: 100%;

}

h3 {
  margin: 0 0 1em 0;

}

/****************************************
HEADING
*****************************************/

header {
  float: left;
  margin: 0 0 30px 0;
  padding: 0;
  width: 100%;

}

#logo {
  text-align:center;
  margin: 0;   
  padding-left: 20px;
}

h1 {
  font-family: 'Open Sans', sans-serif;
  margin: 15px, 0;
  font-size: 1.75em;
  font-weight: normal;
  line-height: 0.8em;
  padding-top: 15px;

}

h2 {
  font-size: 1.25em;
  margin: -5px 0 0;
  font-weight: normal;
}

h3 {
  font-size: 1.25em;
  margin: -5px 0 0;
  font-weight: normal;
}



/****************************************
NAVIGATION
*****************************************/

nav{
  text-align: center;
  padding: 10px 0;
  margin: 20px 0 0; 
 }

nav ul {
  list-style: none;
  margin: 0 10px;
  padding: 0;
}

nav li {
  display: inline-block;
}

nav a {
  font-weight: 800;
  padding: 15px 10px;
}
/****************************************
Footer
*****************************************/

footer {
  font-size: 0.75em;
  text-align: center;
  clear:both;
  padding-top: 50px;
  color: #ccc;  
}

.social-icon {
  width: 30px;
  height: 30px;
  margin: 0 5px;
}
/****************************************
Page Portfolio
*****************************************/

#gallery{
margin: 0;
padding: 0;
  list-style: none;
}

#gallery li {
  float: left; 
  width: 45%;
  margin: 2.5%;
  background-color: #f5f5f5
  color: #bdc3c7
}

#gallery li a p {
  margin: 0;
  padding: 5%;
  font-size: 0.75em;
  color: #bdc3c7;
  text-align:center

}



/****************************************
About  
*****************************************/
.profile-photo {
  display:block;
  max-width: 500px;
  margin:0 auto 0;
  padding-top: 30px;
  border-radius: 75%;

}

/****************************************
Page Contact
*****************************************/

.contact-info {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.95em;
  }

.contact-info a{
  display: block;
  min-height: 30px;
  background-repeat: no-repeat;
  background-size: 30px 30px;
  padding: 0 0 0 30px;
  margin: 0 0 10px
}

.contact-info li.phone a {
  background-image: url('../img/phone.png');
}

.contact-info li.mail a {
  background-image: url('../img/mail.png');
}

.contact-info li.facebook a {
  background-image: url('../img/facebook.png');
}



/****************************************
COLOURS
*****************************************/

/* site body */
body {
  background-color: #fff;
  color: #999;
}

/* Green Header */
header {
  background-color: #6ab47b;
  border-color: #439c57;
}

/* navbackground on mobile devices */
nav {
    background-color: #439c57;
}

/* logo text */
h1, h2 {
  color: #fff;
}

/* links */
a {
  color: #6ab47b;
}




/* nav links*/
nav a, nav a:visited {
  color: #fff;
}

/* selected nav link */
nav a.selected, nav a:hover  {
 color: #32673f 
}

@media screen and (min-width: 480px) {

  /****************************************
TWO COLUMN LAYOUT
*****************************************/
  #primary {
    width: 50%;
    float: left;
  }

  #secondary {
    width: 40%;
    float: right;    
  }
}

@media screen and (min-width: 640px) {


  /****************************************
Page: Portfolio
*****************************************/

#gallery li {
 width: 28.33333%; 
}

#gallery li:nth-child(4n) {
  clear: left;
}


  /****************************************
Page: ABOUT
*****************************************/

.profile-photo {
  float: left;
  margin: 0 5% 80px 0;
}

}


@media screen and (min-width: 640px) {

/****************************************
Page: HEADER
*****************************************/

  nav {
    background: none;
    float: right;
    font-size: 1.125em;
    margin-right: 5%;
    text-align: right;
    width: 45%;    
  }

  #logo {
    float: left;
    margin: left;
    text-align: left;
    width: 45%;
  }

h1 {
  font-size: 2.5em;
}

h2 {
  font-size: 0.825em;
  margin-bottom: 20px;
}

header {
    border: 5px solid #599a68;
    margin-bottom: 60px;

  }

}